Jesus, Krishna, Budda!

I've migrated to EntLib 5.0, but classes like ISymmetricCryptoProvider are not recognized anymore. Funny to say that Data, Logging and other blocks are working compiling fine.

Here's the problematic class:

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;//-->it's not working anymore
using Microsoft.Practices.EnterpriseLibrary.Security.Cryptography;//-->it's not working anymore

namespace MyClassLibrary.Security.EnterpriseLibrary
{

    public sealed class Crypto
    {

        public static ISymmetricCryptoProvider MyProvider
        {
            get 
            {
                //IConfigurationSource is not recognized either, neither SystemConfigurationSource
                IConfigurationSource cs = new SystemConfigurationSource();
                SymmetricCryptoProviderFactory scpf = new SymmetricCryptoProviderFactory(cs);
                ISymmetricCryptoProvider p = scpf.CreateDefault();
                return p; 
            }
        }

The references are fine on project too. I really don't know why this particular project it's causing too many trouble on VS2010! Older references were deleted, project was cleaned, rebuilt, but can't make it compile :-(

The references are:

Microsoft.Practices.EnterpriseLibrary.Common
Microsoft.Practices.EnterpriseLibrary.Logging
Microsoft.Practices.EnterpriseLibrary.Logging.Database
Microsoft.Practices.EnterpriseLibrary.Security
Microsoft.Practices.EnterpriseLibrary.Security.Cryptography

Why some namespaces can be found while others can't?